I don't know if it's intended, thus I rather ask:
Only 1 player at a time can access a shulker box, not several players at the same time.
Basically like with Villagers where only 1 player can trade with them, not 2 at the same time.

It'd be great to know if this is intended.
As it is another type of chest and other chest types can all be accessed at the same time by several players, it'd be from my perspective desirable to have the same for shulker boxes.